before 900;Middle Englishmad (adj.), madden (intransitive v., derivative of the adj.); Old Englishgemǣd(e)d, past participle of *gemǣdan to make mad, akin to gemād mad, foolish; cognate with Old Saxongemēd,Old High Germangimeit foolish

Related forms

half-mad, adjective

half-madly, adverb

half-madness, noun

quasi-mad, adjective

quasi-madly, adverb

unmad, adjective

unmadded, adjective

Synonyms

1. lunatic, maniacal, crazed, crazy. 2. furious, exasperated, raging, wrathful, irate. 4. ill-advised; unsafe, dangerous, perilous. Mad,crazy,insane are used to characterize wildly impractical or foolish ideas, actions, etc. Mad suggests senselessness and excess: The scheme of buying the bridge was absolutely mad. In informal usage, crazy suggests recklessness and impracticality: a crazy young couple.Insane is used with some opprobrium to express unsoundness and possible harmfulness: The new traffic system is simply insane.5. frenzied.

Antonyms

4. sensible, practical; sound, safe.

Usage note

Mad meaning “enraged, angry” has been used since 1300, and this sense is a very common one. Because some teachers and usage critics insist that the only correct meaning of mad is “mentally disturbed, insane,” mad is often replaced by angry in formal contexts: The president is angry at Congress for overriding his veto.

Emerged in Middle English to replace the more usual Old English word, wod (see wood (adj.)). Sense of "beside oneself with excitement or enthusiasm" is from early 14c. Meaning "beside oneself with anger" is attested from early 14c., but deplored by Rev. John Witherspoon (1781) as an Americanism. It now competes in American English with angry for this sense. Of animals, "affected with rabies," from late 13c. Phrase mad as a March hare is attested from 1520s, via notion of breeding season; mad as a hatter is from 1829 as "demented," 1837 as "enraged," according to a modern theory supposedly from erratic behavior caused by prolonged exposure to poison mercuric nitrate, used in making felt hats. For mad as a wet hen see hen. Mad money is attested from 1922; mad scientist is from 1891.